1. Field of the Invention
This invention relates generally to concrete product making machinery and more particularly to structures for assisting in the exchange of one mold box with another within a concrete products forming machine (CPM+).
2. Description of the Prior Art
Concrete Products Machines are complex machines capable of forming concrete products of varying shapes and sizes quickly and in such a way that the freshly formed concrete can be transported to a curing room for hardening without damage to the product. Concrete products come in a variety of sizes, shapes, and structural requirements which result in different concrete mix designs, ingredients, molds configurations, and resultant settings of the machine. Ingredients range widely worldwide and each change to the mix design requires changes to the forming machine settings. Aggregates can include volcanic cinders, crushed rock of many types, natural river rock, expanded clay and shale, and power station waste fly ash to name a few. Likewise, many different types of cement are used as a binder with color oxides and admixes of many types. Finished product shapes, sizes, and heights all require separate molds that are used in the forming machine and each requires different settings of the forming machine. And finally, structural requirements of the finished products change from product to product. A concrete paver may require extremely high densities, strengths, and resistance to liquid absorptions. A light weight masonry unit may have a low minimum strength requirement with a maximum desired unit weight. An architectural masonry unit will require uniform texture of the exposed face throughout the length and width of the exposed unit face. All these variables require unique adjustments and machine settings to form finished products properly.
Prior art machines for forming concrete products within a mold assembly include a product forming section comprising a stationary frame, an upper compression beam and a lower stripper beam. The mold assembly includes a head assembly that is mounted on the compression beam, and a mold box that is mounted on the frame and receives concrete material from a feed drawer. An example of such a system is shown in U.S. Pat. No. 5,807,591 which describes an improved concrete products forming machine (CPM) assigned in common to the assignee of the present application and herein incorporated by reference for all purposes.
In use, the feed drawer moves concrete material over the top of the mold box and dispenses the material into the contoured cavities of the mold box. The feed drawer typically includes an agitator assembly within the drawer that operates to break up the concrete and improve its consistency prior to dropping it into the mold. As the concrete material is dispensed, a vibration system shakes the mold box to spread the concrete material evenly within the mold box cavities in order to produce a more homogeneous concrete product. A wiper assembly, mounted to the front of the feed drawer, acts to scrape excess concrete from the shoes when the feed drawer is moved to an operative position above the mold box.
After the concrete is dispensed into the mold cavities, the feed drawer retracts from over the top of the mold box. A spreader, bolted separately to the front of the feed drawer, scrapes off excess concrete from the top of the mold when the feed drawer is retracted after filling the mold cavities. The compression beam then lowers, pushing shoes from the head assembly into corresponding cavities in the mold box. The shoes compress the concrete material during the vibration process. After compression is complete, the stripper beam lowers as the head assembly pushes further into the cavities against the molded material. A molded concrete product thereby emerges from the bottom of the mold box onto a pallet and is conveyed away for curing and a new pallet moved in its place beneath the underside of the mold box.
The mold box and head assembly are matched together and configured to form concrete products in a specific shape, size, and number. Each product configuration requires a different mold. When the operator desires the CPM to produce products in different configurations, the mold box must be detached from mounts on the CPM and removed along with the head assembly. A different mold box and head assembly must then be moved into place and mounted within the CPM.
The business model has changed from a time where concrete products plants used to have a relatively narrow product offering and finished products were normally made in large production runs for stock storage in a yard. Currently, production plants are required to offer a wide range of finished products in both product configuration and color and rather than producing large quantities for stocking purposes these plants now fill orders in a ‘just in time’ production mode. This requires quick product change-over in the production plant and quick production startups of new products.
Conventional methods for changing mold assemblies in a CPM are typically labor intensive and result in a lot of machine downtime, leading to lost revenue. This is further complicated when exchanging mold assemblies for products of one height with mold assemblies for products of another. Product height changes thus result in even more downtime as various components of the CPM are adjusted to accommodate such a change.
Accordingly, there is need for an improved system and method for better automating the process for changing mold assemblies within a concrete products forming machine that minimizes these drawbacks.